The present invention relates to sprockets and more particularly, to a sprocket with a thin body, and a method for manufacturing such a sprocket.
A known sprocket generally includes an annular body, and a plurality of integral teeth arranged on the peripheral edge of the body at equal intervals. Typically, such a sprocket is mounted on the drive or driven wheel of a motorcycle and is operatively associated with a chain. To improve fuel economy, there is a need in the motorcycle industry to reduce the weight of a motorcycle. An attempt has been made to simply reduce the thickness of the overall sprocket. However, a reduction in the thickness of the teeth requires a corresponding reduction in the width of the chain and prevents the use of an existing chain. This results in an increase in the production costs of the mechanism. Also, a narrow chain lacks durability as compared with the existing chain.
Accordingly, it is an object of the present invention to provide a sprocket which has a reduced weight and which enables the use of the existing chain.
To achieve this object, the present invention provides a sprocket comprising a substantially annular body, and a plurality of teeth arranged on the peripheral edge of the body and having a thickness greater than that of the body.
As the thickness of the teeth is greater than that of the body which occupies a substantial part of the sprocket, the sprocket can be reduced in weight and production costs. The teeth are thick enough to readily correspond with the width of the existing chain. In other words, the teeth are sufficiently thick to accept the existing chain. The present invention thus enables the use of the existing chain and enjoys the strength of the existing chain.
The present invention provides a sprocket comprising a substantially annular body, and teeth formed on the peripheral edge of the body, wherein the body has a thickness less than that of the teeth.
As the thickness of the body is less than that of the teeth, and the body occupies a substantial part of the sprocket, the sprocket can be reduced in weight and production costs. The teeth are thick enough to readily correspond with the width of the existing chain. The present invention thus enables the use of the existing chain and enjoys the strength of the existing chain.
The present invention also provides a sprocket comprising a substantially annular body having a first side, an opposite, second side, a peripheral edge, and a central axis extending centrally through the first and second sides, and a plurality of teeth arranged on the peripheral edge of the body, wherein the teeth include a first step extending radially outwardly from the first side of the body, a first side connected to the first step and extending substantially parallel to the first side of the body, a second step extending radially outwardly from the second side of the body, a second side connected to the second step and extending substantially parallel to the second side of the body, a peripheral wall extending along the peripheral edge of the body and between the first side and the second side of the teeth, and a plurality of recesses formed in the peripheral wall of the teeth.
As the thickness of the teeth is greater than that of the body which occupies a substantial part of the sprocket, the sprocket can be reduced in weight and production costs. The teeth are thick enough to readily correspond with the width of the existing chain. The present invention thus enables the use of the existing chain and enjoys the strength of the existing chain. Further, with the recesses in the peripheral wall of the teeth, the teeth have a larger area to dissipate more heat. Heat is generated by friction when the teeth of the sprocket are drivingly engaged with a chain. Such heat is dissipated through the recesses. The chain is substantially free from thermal expansion or elongation. This results in an increase in the durability of the chain. Advantageously, the recesses provide a path along which dirt or mud is removed from the chain and helps prevent dirt from adhering to the teeth. This results in a decrease in the amount of friction between the chain and the sprocket and thus, in an increase in the service life of the chain and sprocket.
The present invention additionally provides a sprocket comprising a body having a peripheral edge, and teeth formed on the peripheral edge of the body and including respective recesses formed in the peripheral wall of the teeth.
With the recesses in the peripheral wall of the teeth, the teeth have a larger area to dissipate more heat. Heat is generated by friction when the teeth of the sprocket are drivingly engaged with a chain. Such heat is dissipated through the recesses. The chain is substantially free from thermal expansion or elongation. This results in an increase in the durability of the chain. Advantageously, the recesses provide a path along which dirt or mud is removed from the chain and helps prevent dirt from adhering to the teeth. This results in a decrease in the amount of friction between the chain and the sprocket and thus, in an increase in the service life of the chain and sprocket.
According to another aspect of the present invention, there is provided a method for manufacturing a sprocket which comprises a first step of preparing a sprocket which includes a body having a peripheral edge, and teeth arranged on the peripheral edge of the body and having a thickness substantially equal to that of the body, and a second step of increasing the thickness of the teeth so that the teeth are made thicker than the body.
As the body which occupies a substantial part of the sprocket is thin, the sprocket can be reduced in weight and production costs. The teeth are thick enough to readily correspond with the width of the existing chain. The present invention thus enables the use of the existing chain and enjoys the strength of the existing chain.
The present invention also provides a method for manufacturing a sprocket which comprises a first step of preparing a workpiece having a peripheral edge, and a second step of forming a plurality of teeth on the peripheral edge of the workpiece at given intervals, with the teeth having a thickness greater than that of the workpiece.
As the body which occupies a substantial part of the sprocket is thin, the sprocket can be reduced in weight and production costs. The teeth are thick enough to readily correspond with the width of the existing chain. The present invention thus enables the use of the existing chain and enjoys the strength of the existing chain. Moreover, the teeth are made thicker than the rest of the workpiece during formation of the teeth. This results in a decrease in the number of production steps and costs of the sprocket.
The present invention also provides a method for manufacturing a sprocket which comprises a first step of preparing a sprocket including a body having a peripheral edge, and teeth arranged on the peripheral edge of the body and having a thickness equal to that of the body, and a second step of decreasing the thickness of the body so that the body is formed to be thinner than the teeth.
As the body which occupies a substantial part of the sprocket is made thin, the sprocket can be reduced in weight and production costs. The teeth are thick enough to readily correspond with the width of the existing chain. The present invention thus enables the use of the existing chain and enjoys the strength of the existing chain.
According to a further aspect of the present invention, there is provided a circular toothed disk comprising an annular body having a peripheral edge, and teeth arranged on the peripheral edge of the body and having a thickness greater than that of the body, wherein the teeth have recesses formed in the peripheral wall of the teeth.
The present invention also provides a circular toothed disk comprising an annular body having a peripheral edge, and teeth arranged on the peripheral edge of the body, wherein the body has a thickness less than that of the teeth, and the teeth have recesses formed in the peripheral wall of the teeth.
According to a still further aspect of the present invention, there is provided a machine for manufacturing a sprocket, wherein a plurality of teeth are formed on the peripheral edge of a workpiece at given intervals and have a thickness greater than that of the workpiece. The machine comprises a tooth forming tool rotatably pressed against the workpiece, a drive adapted to drivingly rotate the tooth forming tool, and a transfer unit for reciprocatingly moving the tooth forming tool and the drive relative to the workpiece.
The teeth are formed in the peripheral edge of the workpiece while at the same time, the teeth are made thicker than the rest of the workpiece. The present invention is thus capable of reducing the number of production steps and the production costs of the sprocket.
Other features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, claims and drawings.